Simulation Pro 2011 - Stagnation due to oscillations

[Anonymous]

I put this problem down for a while since I have the bruises on my head to show for beating my head against the wall. I understand CFD is the hardest of all FEA.

The stagnation due to oscillations seems to be a reoccurring problem.

My problem posted here

http://forums.autodesk.com/t5/Autodesk-Simulation/Fluid-Flow-Q-does-not-equal-VA/m-p/3232176/highlig...

http://forums.autodesk.com/t5/Autodesk-Simulation/Counter-flow-concentric-tube-heat-exchger-Incroper...

Is like Spencer's posted here

http://forums.autodesk.com/t5/Autodesk-Simulation/Steady-Fluid-Flow-Load-Stepping/m-p/3075524/highli...

and ForrestJudd here

http://forums.autodesk.com/t5/Autodesk-Simulation/Multiphysics-2012-Pressure-Solution-Convergence-Is...

My problem was much like Spencer's and it does not look like he reached a final solution. I'd be interested in where ForrestJudd put the refinement points. I'd agree that if heat transfer is coupled with fluid analysis, there's major descrepencies.

I think the stagnation is causing it. I have a few more turns than spencer.

Any suggestions guys? Astro, Joey, etc? I'd be interested in both LES and k-epsilon with Mixed GLS and refinement points

[Anonymous]

You Hoo #AstroJohn, #Hup, #JoeyX and thoughts?

[Anonymous]

AstroJohn

Any idea where one would strategically put refinement points to eliminate stagnation due to oscillations? I am taking the hint from Forrest Judd's thread but not sure where to place the points. I have a hunch the stagnation is causing very questionable results.

[Anonymous]

#AstroJohn, #Joey.X, any ideas? I've been through letting SIM Pro 2011 automatically place the refinement points. Engineer intuition just screams that the stagnation due oscillations (SDO) is causing the problems with flow, and ultimately, the the coupled heat transfer. 

I was getting anywhere from 1-6 (SDO) warnings with steady state

With unsteady I get 8 (SDO) warnings with 10 load steps.

It is a curved conduit (3/8") with turbulent flow. Tet mesh (95%). Maybe SIM Pro just does not like fluid flow in bends?